ALLOS REPORTS RH1 TRIAL DATA

November 18, 2005

Allos Therapeutics has reported data from an ongoing, multicenter, Phase I dose-escalation
study of the anticancer agent RH1.

In the study, patients with advanced solid tumors refractory to other chemotherapy
regimens are being administered increasing doses of RH1. RH1 is being administered
as a 10- to 30-minute intravenous infusion on Day 1 and 5, every three weeks
for up to six cycles.

RH1 is a small molecule chemotherapeutic agent that is bioactivated by the enzyme
DT-diaphorase, or DTD, which is over-expressed in many tumors relative to normal
tissue, including lung, colon, breast and liver tumors. The bioactivated form
is a potent cytotoxic agent that induces DNA inter-strand cross-linking. Because
RH1 is bioactivated in the presence of DTD, it has the potential to provide
targeted drug delivery to these tumor types while limiting the toxicity to normal
tissue.